\(x\) is a random variable that follows a uniform distribution with the following probability density function:
\[f(x) = \left\{\begin{matrix}
\frac{1}{14} & (a \leq x \leq b) \\
0 & (\text{elsewhere}).
\end{matrix}\right. \]
If the value of \(a+b\) is \(20,\) what is the value of \( a \times b?\)

\(X\) is a random variable that has a continuous uniform distribution with the probability density function
\[f(x) = \left\{\begin{matrix}
\frac{1}{26} & (5 \leq x \leq 31) \\
0 & (\text{elsewhere}).
\end{matrix}\right. \]
Then what is the variance of the distribution?